2018 in San Diego: Mostly dry and warm; what does 2019 hold?

A woman runs across B Street while on 6th Avenue during a heavy downpour in downtown San Diego on Dec. 6, the city's wettest day of 2018. A total of 1.8 inches of rain fell that day.

A woman runs across B Street while on 6th Avenue during a heavy downpour in downtown San Diego on Dec. 6, the city's wettest day of 2018. A total of 1.8 inches of rain fell that day. (Hayne Palmour IV / San Diego Union-Tribune)

Robert Krier

San Diego’s weather in 2018 was almost uniformly warm and dry. Until late in the year, when it was neither.

2019 begins with its own personality: cool days and cold nights, with a couple of storms over the next week that should get the month off to a fairly wet start. Rain is expected to begin Saturday night and continue off and on through Sunday evening. Another storm should arrive Wednesday or Thursday, according to the National Weather Service.

That’s quite a change from the bulk of 2018 — until December arrived.

“What we’ve seen over the last couple of weeks is representative of (El Niño),” said Matt Moreland, the meteorologist in charge of the National Weather Service’s office in Rancho Bernardo. “We are definitely in an active pattern that will last into mid-January.”

Moreland said he could discuss upcoming weather and forecasts, but because of the partial government shutdown, he was not authorized to comment on a recap of 2018’s weather.

When 2018 started, El Niño was nowhere in sight. In fact, San Diego had just emerged from one of the driest falls in city history. Only 0.09 of an inch of rain had fallen from Oct. 1 to Dec. 31, 2017. January 2018 brought one very wet day: Jan. 9, when 1.57 inches fell, but that was about it.The month overall was drier than normal, and that pattern held until December, which had 3.02 inches and was the only month wetter than normal.

February, usually the city’s wettest month with an average of 2.27 inches, delivered just 0.36 of an inch. March, on average San Diego’s third wettest month with 1.81 inches, mustered just 0.95 of an inch. April brought only 0.02.

The dry late winter and spring, also felt in the county’s backcountry, created prime wildfire conditions. The West fire flared in July, caused evacuations in Alpine, destroyed 18 structures and damaged eight more. But San Diego County dodged the massive, uncontrollable and devastating fires that ravaged much of California in 2018.

In terms of temperature, May was 2018’s anomaly. The month finished 0.5 of a degree cooler than normal. It was the only month of the year that wasn’t at least one degree warmer than normal, and it was the first month in 4½ years that was cooler than normal.

In 2018, San Diego had its second warmest January on record, its fifth warmest July, a November that tied for the third warmest, and the warmest August the city has ever seen, with records going back to 1874.

August was a particularly miserable month around the county. Utility bills soared as many people ran their air conditioners around the clock. The daytime high peaked at 91 degrees Aug. 7, but it was the nights that brought the most misery.

In San Diego, the temperature never dropped below 70 degrees all month — even in the dead of night. The low of 77 degrees on Aug. 9 set the record for the warmest August night in city history. The next day broke that record and matched the highest minimum temperature (78) ever recorded in San Diego — for any month of the year. Records for the highest minimum were set or tied 10 of the first 12 days of the month.

The record warmth was blamed on three factors: a very warm air mass that hung out over much of the West; extremely high humidity; and record-high sea-surface temperatures off the county coast.

At Scripps Pier, where ocean temperatures have been monitored for 102 years, on Aug. 1 the water hit 78.6 degrees, which broke the the all-time record that had stood since 1931. Two days, later the reading was 78.8. Then it climbed to 79.2 and finally maxed out at 79.5 on Aug. 9. Other spots along the county coast were showing water readings of 80 degrees or more.

With waters that warm, when the usual onshore breezes kicked in, they brought no relief to the coast communities.

When fall arrived, the warmth continued. The San Diego was warmer than normal for 65 straight days, from Oct. 24 to Dec.27. On the year, 68 days were cooler than the daily climatological norm, two were exactly normal, and 295 were warmer than normal.

Overall, 2018 tied with 2016 as San Diego’s sixth warmest year on record. Every year since 2014 in San Diego has been in the top 9; 2014 was the warmest, and 2015 was the second warmest.

The high temperature in 2018 was 96, on July 6, and the low for the year was 41, on Dec. 29.

December not only had the year’s coldest day, it also had its wettest. On Dec. 6, 1.80 inches of rain fell in about seven hours. The storm included an impressive, loud thunderstorm that knocked out power around downtown San Diego and caused minor street flooding.

A cold storm also dropped rain on New Year’s Eve and produced a water spout and funnel cloud off the North County coast.

Now the question is, will the wet pattern in December carry over into 2019? El Niño, which tilts the odds toward a wet winter in Southern California, is forming in the central Pacific. But recent El Niños haven’t lived up to their promise.

The “monster” El Niño of 2015-16, which came in the midst of a multi-year drought and was supposed to provide the closest thing to a guaranteed wet winter, fizzled and left the state dry. The El Niño forming now is not nearly as strong.

The Climate Prediction Center’s latest projection for the winter calls for equal chances of wet, dry or normal weather from January through March.The National Weather Service’s Moreland said that although the current pattern creates the potential for storms through mid-January, it is difficult to say what will happen beyond that point.